1. Field of the Invention
This invention concerns directional control of permanent magnets, and it is particularly applicable to the simultaneous control of a plurality of rotors that are rotatable about transversely spaced coplanar axes. Such rotors are suitable for adjusting the attitudes of louvers of inaccessible Venetian blinds.
2. Description of the Prior Art
Environmental screens have been described in the patent literature having ribbon-like louvers supported only at their ends, each end being attached to a permanent magnet rotor. The angle of the rotors is determined by equilibrium between a control torque produced by a direct electromagnetic field and a restoring torque that tends to maintain each rotor at a predetermined angle of repose. Although only one long coil is required for each side of the screen, the two coils are relatively expensive to manufacture. Furthermore, a small amount of electrical power is continuously used to hold the rotors at other than the angle of repose.